Starch is a major component of ruminant diets, often comprising over 30% of lactating dairy cow diets and over 60% of diets for beef feedlot finishing diets on a dry matter (DM) basis. In ruminants, starch can be fermented to volatile fatty acids in the rumen, digested to glucose in the small intestine, or fermented to volatile fatty acids in the large intestine. Degradability of dietary starch affects site of digestion and whole tract digestibility. Site of digestion, in turn, affects fermentation acid production, ruminal pH, microbial yield, and efficiency of microbial protein production. All such factors can affect the productivity of ruminant animals. Many factors affect site of starch digestion in ruminants including DM intake, forage content of the diet, processing, and conservation methods. Grain processing is costly but is often justified economically to increase degradability of starch. High moisture corn grain generally has higher starch degradability than dry corn grain. This is partly because vitreousness of corn endosperm increases with maturity at harvest (Philippeau and Michalet-Doreau, 1997). In addition, ensiling corn increases starch degradability (Philippeau and Michalet-Doreau, 1999). Stock et al. (1991) reported that solubility of endosperm proteins was highly related to moisture level in high moisture corn and solubility increased with time of storage. Endosperm proteins seem to decrease access of starch granules to amylolytic enzymes.
Endosperm type also affects starch degradability, and it is well known that the proportion of vitreous and floury endosperm varies by corn hybrid. Dado and Briggs (1996) reported that in vitro starch digestibility of seven hybrids of corn with floury endosperm was much higher than that for one yellow dent hybrid. Philippeau et al., (1996) reported much higher in situ ruminal starch degradation for dent corn compared to flint corn harvested at both the hard dough stage and mature (300 g kg−1 and 450 g kg−1 whole plant DM, respectively). Grain (grain refers broadly to a harvested commodity) processing increases the availability of starch in floury endosperm much more than starch in vitreous endosperm (Huntington, 1997). Cells in the floury endosperm are completely disrupted when processed, releasing free starch granules (Watson and Ramstad, 1987). In contrast, there is little release of starch granules during processing for vitreous endosperm because the protein matrix is thicker and stronger. It is generally assumed that corn with a greater proportion of floury endosperm might have greater starch digestibility and be more responsive to processing.
Neutral detergent fiber (NDF) from forage is an important component in many ruminant diets. Forage NDF is needed to stimulate chewing and secretion of salivary buffers to neutralize fermentation acids in the rumen. Increasing the concentration of NDF in forage would mean that less NDF would have to be grown or purchased by the farmer. Thus, crops with higher than normal NDF concentrations would have economic value as a fiber source. However, that value would be reduced or eliminated if the higher NDF concentration resulted in lower digestibility and lower available energy concentrations. Beck et al., WO/02096191, recognized the need for optimizing starch degradability by careful selection of corn having specific grain endosperm type, in view of the ruminal rate of starch degradation, moisture content, and conservation methods used, combined with selection of corn for silage production with specific characteristics for NDF content and NDF digestibility.
Selecting a plant based on its genetics for inclusion in a feed formulation results in inconsistent ruminant animal productivity. For example, selection of a corn hybrid based on its grain endosperm type will yield inconsistent ruminant animal productivity over time. Thus, the present invention includes analyzing the starch and fiber digestibility characteristics of grain and a crop plant for use as forage in real time. The present invention also includes preserving the identity of the grain and the crop plant used for forage based on their starch and fiber digestibility characteristics. The present invention further includes using the grain and crop plant used for forage from one or more identity preserved crop plants to create feed formulations that result in optimum productivity of the ruminant animal.